Electrical Activity of the Diaphragm in a Small Cohort of Term Neonates

BACKGROUND: Electrical activity of the diaphragm (Edi) has been proposed as a parameter to evaluate respiratory function. Normative values of electrical activity of the diaphragm in full-term neonates are not known. This is a small case series to establish preliminary values of E di in term neonates and to determine how these values vary while awake and asleep and during feeding states. METHODS: Three term neonates in room air and nippling feeds at the time of the study were observed for 4 hours. E di was measured by electrodes within a nasogastric tube positioned at the level of the diaphragm. Respiratory rate and heart rate were also recorded. Time while awake and asleep were noted. Feeding states included feeding, 30 min pre-prandial, and 30 min post-prandial. Statistics were analysis of variance and t tests, with P < .05. RESULTS: Mean E di peak was 11 5 V. Mean Edi minimum was 3 2 V. Edi peak and minimum were higher while awake. E di peak was lower post-prandial. Respiratory rate was higher post-prandial. CONCLUSIONS: These are the first preliminary values for E di in neonates. Higher Edi peak while awake may reflect larger tidal volume to meet increased metabolic requirements when awake and active. Post-prandial lower E di peak and higher respiratory rate may indicate compensation for decreased tidal volume from increased intra-abdominal pressure. These data may be useful in identifying respiratory pathology in neonates and monitoring progression toward respiratory health. Key words: diaphragm excitation; respiration; feeding states; sleep states; electromyographic activity; Neurally Adjusted Ventilatory Assist; NAVA. [Respir Care 2012;57(9):1483–1487. © 2012 Daedalus Enterprises]